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Sunday, 17 July 2016

An American Yankee in GABTU's Court

The USSR was the second country, after Great Britain, to receive tanks from the United States. Among them were M3 light tanks. According to American data, 1336 tanks of this type were sent to the USSR, a quarter of the overall volume of Light Tank M3 production. Out of all tanks sent, 440 (including M3A1 tanks) were lost during transport.

Domestic literature often calls the M3 weakly armoured and poorly armed. This evaluation is surprising, especially when you compare the tank to the Soviet T-70. In order to truly evaluate the American tank in the Soviet Union, we must consult archive documents.

Lapses in Shipments
As with British tanks, information on technical characteristics of American tanks was incomplete and outdated. Some kind of modern data appeared in September, but a comical situation occurred with the Light Tank M3. Somehow, data about this tank and the prospective Light Tank T9 (future M22) was mixed into one. Its mass was 7-10 tons, armour was 30 mm thick, and crew consisted of 3-4 men. The maximum speed of this "combined" tank was 80 kph, and it was armed with a 37 mm cannon and three machineguns.

The main tank of the American army was considered to be the M2A4, even though production of that tank ceased in March of 1941. This assumption became the foundation of a mistake that was later cited by many armoured historians. More on that later.

The real characteristics of the Light Tank M3 were received in the USSR only on November 13th, 1941. They were sent to the Deputy People's Commissar of Foreign Trade A.D. Krutikov by Colonel Faymonville, a member of the American embassy in Moscow. Faymonville played an important role in the shipment of tanks to the USSR, later earning the rank of Brigadier General.

According to documents, an agreement was made by on October 9th, 1941, to purchase 94 Light Tanks M3 along with ammunition and spare parts. A full set of parts was to be shipped with every three tanks, and one gun, machinegun, and set of optical devices for every 20 tanks. A month later, the issue of American specialists who would assist with the usage of tanks. This was beneficial for the US, as their specialists could collect information that would help them further improve the tanks.

One of the documents that set a foundation for the myth that M2A4 light tanks were shipped to the USSR. [The tanks were initially recorded as "American medium" and "American light".]

The tanks were sent along the northern route with British tanks. The six-transport convoy PQ-6 was the first to carry them. On December 9th, 1941, it departed from Iceland, and arrived in Archangelsk without losses on the 20th. The convoy carried 31 Light Tanks M3. The historical misunderstanding arose from here: certain documents say that the convoy arrived with 31 M2A4s. This generated the rumour that these tanks were sent to the USSR.

Even the Americans contradict that theory, and the serial numbers of the tanks sent to the 176th Independent Tank Battalion reveal that it was a mistake. A complaint dated January 12th, 1942, further underlines the fact that these were not M2A4s. According to the complaint, the 31 M3 light tanks that arrived in Archangelsk got there with summer lubricants and a lowered amount of electrolytes. However, the complaints ended there.

Diagram of the turret with the periscope opening from the Stuart Hybrid.

Initially, the American tanks were sent in humble amounts. In March, 26 tanks arrived, 13 more in April. Tanks arriving with the northern convoys were sent to the Gorkiy training center. The situation began to improve when PQ-15 brought 201 tanks. In July, 147 tanks came with PQ-16. The destruction of PQ-17 was a serious loss, as surviving vessels only brought 39 tanks. As a result, shipment of tanks through Baku in the south was organized.

As of September 1st, 1942, 504 tanks arrived in the USSR by arctic convoys, and 104 more through Iran. The tanks that came through the south were sent to the Baku tank school. 57 tanks arrived in September, 15 in October, and 130 in November. 977 American light tanks arrived in the USSR in 1942, 298 of them through the south. Later shipments contained M3A1 tanks, but since they were not recorded separately, it is impossible to determine how many.

Light Tank M3 during trials, May 1942.

Tanks from nearly all production runs were sent to the USSR, except tanks with riveted D37182 turrets. The USSR received tanks with Light Tank M3A1 turrets: with the stabilizer, but without a turret basket or an electric turret traverse mechanism. These tanks were called Stuart Hybrid by the British, but they received no special designation in the USSR. Their shipments began in August of 1942, and added up to a fairly large amount of vehicles (at least 40). This was discovered due to a defect. Tanks of this modification arrived with a gaping hole instead of a commander's periscope in the turret. There as not enough time to figure out what happened to the periscopes, so the holes were welded over.

Lightweight Champion

Despite the fact that the first Light Tanks M3 (M-3 light or M3l in Soviet nomenclature) arrived in December of 1941, their trials weren't rushed. This is connected partially with the fact that the Armoured Vehicle Research Institute (NIIBT) proving grounds were partially evacuated to Kazan. Trials only began in May of 1942, when the institute received a tank with the D38976 turret.

The institute took trials of this tank very seriously. Aside from the usual program, comparative trials were performed with the Medium Tank M3, PzKpfw 38(t), PzKpfw III Ausf H, and Valentine VII. A separate trial in swampy terrain was conducted, where they were joined by the T-60 and T-70. Mobility trials were complemented by gunnery trials where the 37 mm gun was tested against captured vehicles. In conclusion, an examination of the hull design and its materials was performed.

Light Tank M3 from the front. The lack of several details, including the headlights, is noticeable.

Initially, the tank was supposed to travel 1000 km, 300 of them on a highway, 500 on dirt roads, and 200 off-road. In reality, the tank traveled 420 km between May 1st and 13th (225 on a highway, 132 on dirt roads, 63 off-road). This was enough to evaluate the tank's performance.

The same trials evaluated the maximum speed of the vehicle, which was 58 kph in one case and 59.2 kph in another. This matched the Light Tank M2A4's top speed. The American tank was the fastest among all of the tanks tested. The average speed was 37.5 kph on a highway, 22.1 kph on a dirt road, and 17.3 kph off-road. The M3 ate a lot of fuel for a light tank: 135.5 Liters per 100 km on a highway, 198 on a dirt road, and 347 off-road! Since the fuel tank only fit 200 Liters, this caused some concerns. The tank also consumed higher octane gasoline than Soviet tanks.

Light Tank M3 from the left. Judging by the lack of antenna, this tank did not have a radio.

Harry Knox's rubber-metallic tracks also caused many surprises. The track surface was smooth, without any hint of grousers. On muddy terrain, especially when climbing hills, the track design played a cruel joke. Due to insufficient traction, the tank could not climb up a 25 degree slope, even though there was more than engine engine power for it.

Another problem was driving at an angle. The tracks slipped off, and their design was once again to blame. The engine also overheated, causing an interesting result: after a 40 minute march, turning off the ignition left the engine on. The trails were bittersweet: the tank was easy to control, and the driver had good visibility.

Only the shovel is present from all the tank's pioneer tools. This is not a result of looting by locals, but incomplete shipments, which caused a lot of friction between GABTU and the Americans.

Comparative trials in July of 1942 followed. Here, the M3 tank sped up even more, to 60 kph. The average fuel expenditure on a highway, dirt road, and off-road was 136, 176, and 246 L respectively. This indicates that the first stage of trials likely had some problems. However, the tank could still drive less than 100 km off-road. It's not surprising that the British demanded extra fuel tanks for their Stuarts in 1942. To be fair, the PzIII Ausf H consumed 215, 280, and 335 L of fuel respectively, but its off-road range was 95 km.

Climbing a slope. Due to poor traction, this was not possible immediately.

Trials in summer conditions showed that the American light tank still has the same problems while climbing slopes. Even the installation of spurs didn't help. After that, the tank started digging into the dirt instead of sliding on it. However, other tanks did not perform especially well either. The M3 Light demonstrated insufficient traction on 40 degree slopes.

After fording a 1.4 meter deep river, the tank only managed to climb out on a second attempt, also due to bad traction. Meanwhile, the M3 Medium stalled while trying to exit the river and had to be dragged out with a tractor. The same thing happened with the Valentine VII. The PzIII could not achieve even that, since its engine compartment flooded at the 1.3 meter depth mark. The tank only made it 30 meters. The Pz38(t) was a little more successful, making it 35 meters.

The result of driving on a slope. Judging by reports from the front, it could have been worse: the tank could have flipped over.

Swamp driving trials were held separately. A 100 meter long section of a swamp was chosen, passable by people, difficult for a horse, and impossible for wheeled vehicles. The American light tank passed it in both directions, getting stuck only when following its own tracks. The Medium Tank M3 got stuck after driving for 30 meters. The PzIII made it to the 50 meter mark. The Valentine VII and Pz38(t) did not experience any problems in the swamp.

Later, during the second stage of the trials, light T-60 and T-70 tanks replaced the PzIII and Valentine VII. The results were the same, the M3 won again. As for the newcomers, they could cross the swamp, but the suspension became clogged with grass, which caused the T-70 to get stuck during one crossing.

The tank is trying to climb out of the water, and managed on the second try. Pay attention to the driver's windscreen. This was a very useful addition, especially when driving during the winter or in mud.

The finale was gunnery trials. It turned out that the Soviet 45 mm gun and British 40 mm gun could not penetrate 50 mm thick armour. As for the American 37 mm M5 gun, it could penetrate the 50 mm plate on a StuG or the 25+25 mm front of the Pz38(t) from 100 meters. The gun was powerful enough to fight any enemy tank produced in 1941.

The design of the hull and composition of the armour did not impress Soviet specialists. The hull had many riveted connections, and the armour had a large amount of deficit nickel and molybdenum additives.

Fast, but Large and Flammable

The new American light tanks were first used by the Red Army in May of 1942, during the Kharkov operation. Later, the M3 spread itself to other parts of the front, and were used in mass amounts closer to late July, when more of the tanks arrived. The subject of the tank's career in the Red Army is broad, so let's focus on its reception.

The tank is driving through a swamp.

During talks about ordering M3 tanks in November of 1941, the tank was compared to the T-50. The Soviet tank was superior in its range and armour, but it was a little heavier and slower. According to documentation, the American tank cost $42,787, or 226.771 rubles using the 1940 exchage rate. The T-50 only cost 150,000 rubles, but its production has not yet started, and its price was estimated to be twice as much in only June of 1941. As a result, the analogue of the M3 was the T-70, which cost a little under 64,000 rubles by the spring of 1943. However, the T-70 was worse than the American tank in almost every parameter, and GABTU was not happy with the one-man turret on the tank.

The first reviews of M3 tanks started coming in during March of 1942. Engine defects were the most serious among all reported problems. To start, the RPM limiter did not work due to poor regulation. During backfires, the hoses often caught fire. This defect was connected with a lack of a fire suppressant net. There were also problems with engaging the first gear.

Cracks were found in one tank's turret, and the hatches were torn off their hinges on two more. American specialists were brought in to resolve these issues. Amtorg translated the manuals. The domestic manuals turned out to be more complete than foreign ones, and had a different structure. At the same time, tighter control of incoming tanks was implemented. This was most important when it came to radios, as they were simply missing on many tanks. The issue of spare parts was also a pressing one, and there were many letters written on the subject.

A tank with the D38976 turret was used in the second swamp trial.

The results of trials that consumed so much expensive fuel did not go ignored. On May 23rd, GABTU requested tanks with Guiberson T-1020–4 diesel engines. According to information from American sources, diesel tanks were never sent to the USSR. As for tanks with gasoline engines, B-78 gasoline or B-70 gasoline with a mix of R-9 was proposed instead of 80 octane gasoline. The issue with non-stopping engines was resolved by lowering the RPM to 800-900 for 3-5 minutes, then 400-500 for 2-3 minutes. When starting the engine, one had to be careful to not let gasoline into the intake nozzle, as it would result in a fire. Plus, the gasoline corroded the hoses.

The People's Commissar of Tank Production, Malyshev, had harsh words to say about American tanks in his letter to Stalin on May 2nd, 1942: "After inspecting the American type M-3 (light) and M-3s (medium) tanks that arrived in the USSR, I must make the conclusion that these tanks have low effectiveness in combat and would be quickly destroyed or break down. American tanks have the following serious defects:

The tanks can be lit on fire easily, as the gasoline engine is easily accessible for incendiary fluid.

The rubber track links will wear quickly when driving on stone roads or mud and rock terrain in dry weather, and a tank with these tracks would not be able to move at all in mud, or would drive very slowly at a speed of 3-5 kph."

Practice showed that the concern about the tracks was excessive. The fear of difficult conditions for the driver due to a front transmission were also unfounded. Malyshev's suggestion to order heavy tractors instead of tanks was declined. Malyshev's assertion that American tanks lagged behind Soviet ones by several years was also incorrect.

The M3's gun was effective against any German tank produced in 1941.

An objective opinion about the M3 light tank arrived at GABTU on June 23rd, 192. It came from Lieutenant-General V.S. Tamruchi, who was removed from his role as the commander of the South-Western Front's armoured forces after the Kharkov operation. According to his report, the tank was very maneuverable and easy to drive. Malyshev's assertions about the tracks proved themselves false, as the tank could climb 30 degree slopes in dry weather, and the rubber made the tank much quieter. The suspension overall was admitted to be weak, especially since the rubber tracks slipped and fell off in wet weather.

The armour of the hull was enough to hold a 37 mm round at long ranges. The tank was also very tall, which made it a good target. The tall and narrow hull combined with a narrow track gave it a tendency to flip over at angles of over 20 degrees. The vertical armour plates made ricochets a rarity. Tamruchi's opinion was that additional armour could be installed on the tank. He also had complaints about the engine, which were largely listed above.

Another drawback was the presence of a large amount of rubber in the fighting compartment, designed to protect the crew from injury. In practice, that rubber ended up being the cause of fires, and crews tried to clear it out when possible. The armament was evaluated as powerful, but the use of machineguns in sponsons was called into question. In addition, the installation of a radio meant the removal of one machinegun and 48 shells.

In conclusion, the complaints about thin armour and poor armament of the M3 light tank are unreasonable. The thickness of the armour was comparable to other light tanks of the time period, and the gun had the best penetration characteristics compared to analogous armament. At the same time, the tank had many drawbacks.

Diagram of the tank's armour from the armour evaluation report.

Overall, the negative impressions that accompany the American tank came from the time of its arrival and application. By the summer of 1942, German tanks with thicker armour and more powerful armament arrived on the battlefield. Compared to them, nearly all light tanks became obsolete. Only the British managed a worthwhile modernization of their Valentine tank, equipping it with a new turret and the 57 mm 6-pdr gun.

Additional negativity comes from the fact that many of these tanks remained in use by 1943. As of January of 1944, 424 of these tanks were still in service, or a third of all Light Tanks M3 that arrived in the USSR. 141 tanks were lost by June 1st, but the survivors remained in service. In some units, they lasted towards the end of the war. It's not hard to guess what a tank developed in 1941 would look like in 1944.